Knowledge Bank

The absorption spectra of erbium borohydride in pure and lanthanum borohydride $(La(BH4)3$ $\cdot$ 3THF) mixed crystals at 77, 4.2, and 1.6$\mathrm{<mrow\; data-mjx-texclass="ORD">\circ </mrow>}K$ are reported. The spectral range covered is 3000 to 9000 {\AA} and transitions have been assigned between excited state multiplets and the $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}I15/2$ ground state manifold. Particularly noteworthy are the great differences in numbers of lines and line positions between pure and dilute crystals. These observations are best explained by a magnetically ordered pure crystal. Vibronic transitions have been identified involving both ground and excited states. The overall intensity of electronic and vibronic features is roughly comparable.